1. Field of the Invention
This invention relates to surf boards and other surf riding craft such as body boards and the like. The present invention improves the performance in riding waves by bending and torsional motion of nose and tail segments of the craft relative to the midsection.
2. Description of Related Art
There are currently in use many designs of surf boards, body boards and the like for riding on waves in water. Various designs incorporate stiffening elements in the water craft as well as providing for segmented elements of flexure in such devices.
Currently known designs include the well known body board which most often provides a fairly rigid tail or back one half to two thirds of the board with a flexible nose section. This allows the user to bend the nose for turning the body board.
Other examples of known variable flexure designs include those disclosed in U.S. Pat. Nos. 5,145,430 and 4,887,986. In the first instance a surf riding board has a relatively stiff bottom element with a stiffening spline attached to the top surface. This forms the structural elements of the design. To this are added relatively soft filler pads on each side of the stiffening spline, a top surface for the user to stand on, and rails or edges on the sides. This design provides a relatively uniform structure along the longitudinal dimension of the board.
The second patent disclosure provides for two flexible side portions in the tail section of the surf riding board on each side of a narrow bridge. The two flexible side portions are created primarily in the bottom portion of the board and are designed for stability in difficult water conditions and during maneuvering.
The present invention uses a center stringer with foam core elements located on each side. The center stringer is gently curved upward from center to ends in manufacture to create a spring effect to resist upward bending and to create a tendency to return to the original straight position. A midsection element is bonded to the top and bottom of the center core element to create a flexible strong bond midsection to provide for flexure and torsional motion. When the craft is enclosed with a top skin and bottom skin, the board is structured for torsional motion about the stringer for the nose and tail sections with the relatively flexible midsection and relatively more bending ability in the tail as the stringer is prestressed in this area. This provides for better performance as the twisting and bending in the tail under pressure provides a spring action on release and for maneuvering for turning due to the torsional bending motion.